Sink



FIG. 1 is a perspective view of a sink showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof; and,

FIG. 4 is a left side view thereof, the opposite side being a mirror image of the side shown.

The broken line showing is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a sink, as shown and described. 